<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Hello</title>
</head>
<body>
    <script>
        var socket;
        // 判断当前浏览器是否支持websocket
        if (window.WebSocket) {
            // go on
            socket = new WebSocket("ws://localhost:7000/hello");
            // 相当于channelReado, ev 收到服务器端回送的消息
            socket.onmessage = function (ev) {
                var rt = document.getElementById("responseText");
                rt.value = rt.value + "\n" + ev.data;
            }

            // 相当于连接开启(感知到连接开启)
            socket.onopen = function (ev) {
                var rt = document.getElementById("responseText");
                rt.value = "连接开启了.."
            }

            // 相当于连接关闭(感知到连接关闭)
            socket.onclose = function (ev) {
                var rt = document.getElementById("responseText");
                rt.value = rt.value + "\n" + "连接关闭了.."
            }
        } else {
            alert("当前浏览器不支持websocket")
        }

        // 发送消息到服务器
        function send(message) {
            // 先判断socket是否创建好
            if (!window.socket) {
                return;
            }
            if (socket.readyState === WebSocket.OPEN) {
                // 通过socket 发送消息
                socket.send(message)
            } else {
                alert("连接没有开启");
            }
        }
    </script>

    <form onsubmit="return false">
        <textarea name="message" style="height: 300px; width: 300px"></textarea>
        <input type="button" value="发送消息" onclick="send(this.form.message.value)">
        <textarea id="responseText" style="height: 300px; width: 300px"></textarea>
        <input type="button" value="清空内容" onclick="document.getElementById('responseText').value=''">
    </form>

</body>
</html>